Acid base indicators

THIS PRESENTATION IS FOR THE STUDENTS STUDYING IN SENIOR CLASSES .IT WILL HELP THE CHILD TO RECALL THE CONTENT IN SHORT TIME IT WILL HELP TO BUILD THE STRONG AND CLEAR CONCEPT KNOWLEDGE.

1. ACID –BASE INDICATORS BY: VEENU GUPTA (PGT CHEMISTRY) APS RAKHMUTHI

2. Indicators are substances which indicate the acidic or basic nature of the solution by their colour change. INDICATORS

3. NATURE OF SUBSTANCE WITH CHANGE IN pH

4. There are many types of indicators. Some common types of indicators are: UNIVERSAL INDICATOR NATURAL INDICATORS OLFACTORY INDICATORS SYNTHETIC INDICATORS Types of Indicator :

5. pH RANGE OF COMMONLY USED INDICATORS

6. It is a mixture of organic dyes or several indicators. It shows different colours at different concentrations of hydrogen ions in a solution. UNIVERSAL INDICATOR pH range NATURE OF SOLUTION CHANGE IN COLOUR OF UNIVERSAL INDICATOR 0-2 ACIDIC RED TO PINK 2-4 ACIDIC PINK TO YELLOW 4-7 ACIDIC YELLOW TO GREEN 7 NEUTRAL GREEN 7-10 BASIC GREEN TO BLUE 10-12 BASIC BLUE TO INDIGO 12-14 BASIC INDIGO TO VIOLET

7. Indicators obtained from natural sources are called Natural Indicators. Litmus, turmeric, red cabbage, China rose, etc., are some common natural indicators used widely to show the acidic or basic character of substances. . Natural Indicators:

8. Litmus: Litmus is obtained from lichens belonging to plant division , Thallophyta . The solution of litmus is purple in colour . Litmus paper comes in two colours - blue and red. An acid turns blue litmus paper red. A base turns red litmus paper blue. Turmeric : Turmeric is another natural indicator. Turmeric is yellow in colour . Turmeric solution or paper turns reddish brown with base. Turmeric does not change colour with acid. Red Cabbage : The juice of red cabbage is originally purple in colour . Juice of red cabbage turns reddish with acid and turns greenish with base.

9. Substances which change their smell when mixed with acid or base are known as Olfactory Indicators. For example; Onion, vanilla etc . i ) Onion: Paste or juice of onion loses its smell when added with base. It does not change its smell with acid. ii) Vanilla: The smell of vanilla vanishes with base, but its smell does not vanish with an acid. Olfactory Indicators are used to ensure the participation of visually impaired students in the laboratory. 2. Olfactory Indicator:

10. Indicators that are synthesized in the laboratory are known as Synthetic Indicators. For example; Phenolphthalein, methyl orange, etc. Phenolphthalein is a colourless liquid. It remains colourless with acid but turns into pink with a base. Methyl orange is originally orange in colour . It turns into the red with acid and turns into yellow with base. 3. Synthetic Indicator :

11. COLOUR OF PHENOLPHTHALEIN IN ACIDIC AND BASIC SOLUTION

12. COLOUR OF METHYL ORANGE IN ACIDICAND NEUTRAL SOLUTION

13. INDICATORS AND THEIR COLOURS IN ACIDIC AND BASIC SOLUTIONS Indicator Original Colour of Indicator Colour or nature in Acids Colour or nature in Base RED LITMUS RED NO CHANGE BLUE BLUE LITMUS BLUE RED NO CHANGE TURMERIC YELLOW NO CHANGE REDDISH BROWN RED CABBAGE JUICE PURPLE REDDISH GREENISH YELLOW PHENOLPHTHALEIN COLOURLESS COLOURLESS PINK METHYL ORANGE ORANGE RED YELLOW PETALS OF CHINA ROSE RED MAGENTA OR RED GREEN ONION N/A NO CHANGE SMELL VANISHES VANILLA N/A NO CHANGE SMELL VANISHES

14. THANKS